Browse Prior Art Database

Switchable Communications Interface Wrap Plug

IP.com Disclosure Number: IPCOM000102671D
Original Publication Date: 1990-Dec-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 4 page(s) / 122K

Publishing Venue

IBM

Related People

Harris, HL: AUTHOR [+5]

Abstract

This article describes a device, as shown in Figs. 1-3, which replaces the four conventional wrap plugs used on remote controllers. This device also supports a serial pulse counter and an LCD display used in controller testing.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Switchable Communications Interface Wrap Plug

       This article describes a device, as shown in Figs. 1-3,
which replaces the four conventional wrap plugs used on remote
controllers.  This device also supports a serial pulse counter and an
LCD display used in controller testing.

      The controller supports three different communications
interfaces:  EIA 232D (CCITT V.24/V.28), CCITT V.35, and CCITT X.21.
The wrap plug is used to route transmitted signals back to the
receivers on the communications circuitry to aid in diagnosing
communications interfaces.  A unique wrap plug was required to
support each communication interface.  In addition, V.35 requires two
separate wrap plugs, each wrapping one half of the signals of the
differential lines, for a total of four required wrap plugs.

      A single 25-pin DSUB connector is used for all electrical
interfaces in both the controller and in the switchable wrap plug.  A
four- position rotary switch on the wrap plug energizes the
appropriate relays.  The signals from the 25-pin connector connect
the proper signals required for each wrap connection.

      The wrap plug assumes that the cables connect only those
signals required by that interface so that extra signals on unused
pins do not interfere with the test.  The cables take the signals at
the assigned positions on the DTE side and route them to the correct
position on the DCE side, which has the correct connector defined for
the interface. Communications controller cables were used intact
which defined the wrap connections needed.

      The switchable wrap plug is superior to the four separate wrap
plugs because it allows the same plug to be used for any controller
model being tested.  This simplifies testing.  In addition, because
one model of the controller supports both EIA 232D and CCITT V.35,
two interfaces can be tested on the same controller without
physically swapping wrap plugs, which would have required three
different wrap plugs before.

      The X.21 interface on the controller requires a clock signal to
be supplied during the test, which is included in this circuitry. Pin
Definitions at the 25 Pin-Connector (DTE Side):
      Pin       EIA 232D
       1        shield
       2        232D Transmit Data
       3        232D Received Data/X.21 Indicate Phase B
       4        232D Request to Send
       5        232D Ready for Sending
       6        232D Data Set Ready
       7        Ground
       8        232D Data Channel Received Line Signal
                Detector
       9        X.21 Transmit Phase A, V.35 Transmit Phase B
      10        X.21 Transmit Phase B, V.35 Transmit Phase A
      11        X.21 Control Phas...